• Title/Summary/Keyword: cerium

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Amperometric Immunosensor for Myeloperoxidase in Human Serum Based on a Multi-wall Carbon Nanotubes-Ionic Liquid-Cerium Dioxide Film-modified Electrode

  • Lu, Lingsong;Liu, Bei;Liu, Chenggui;Xie, Guoming
    • Bulletin of the Korean Chemical Society
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    • v.31 no.11
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    • pp.3259-3264
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    • 2010
  • A label-free amperometric immunosensor has been proposed for the detection of myeloperoxidase (MPO) in human serum. To fabricate such an immunosensor, a composite film consisting of N,N-dimethylformamide (DMF), multiwall carbon nanotubes (MWCNTs) and 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMIMBF_4$) suspension was initially formed on a glassy carbon electrode (GCE). Then cerium dioxide ($CeO_2$) dispersed by chitosan was coated on the GCE. After that, MPO antibodies (anti-MPO) were attached onto the nano$CeO_2$ surface. With a noncompetitive immunoassay format, the antibody-antigen complex formed between the immobilized anti-MPO and MPO in sample solution. The immunosensor was characterized by cyclic voltammetry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The factors influencing the performance of the immunosensor were studied in detail. Under optimal conditions, the current change before and after the immunoreaction was proportional to MPO concentration in the range of 5 to $300\;ng\;mL^{-1}$ with a detection limit of $0.2\;ng\;mL^{-1}$.

Effect of Cerium loading on Stability of Ni-bimetallic/ZrO2 Mixed Oxide Catalysts for CO Methanation to Produce Natural Gas

  • Bhavani, Annabathini Geetha;Youn, Hyunki
    • Korean Chemical Engineering Research
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    • v.56 no.2
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    • pp.269-274
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    • 2018
  • All the $Ni-Co-Ce-ZrO_2$ mixed oxides are prepared by co-precipitations methods. Methanation of CO and $H_2$ reaction is screened tested over different fractions of cerium (2, 4, 7 and 12 wt.%) over $Ni-Co/ZrO_2$ bimetallic catalysts are investigated. The mixed oxides are characterized by XRD, CO-Chemisorption, TGA and screened methanation of CO and $H_2$ at $360^{\circ}C$ for 3000 min on stream at typical ratio $CO:H_2=1:1$. In $Ni-Co/CeZrO_2$ series 2 wt.% Ce loading catalyst shows most promising catalyst for $CH_4$ selectivity than $CO_2$, which directs more stability with less coke formation. The high activity is attributed to the better bimetallic synergy and the well-developed crystalline phases of NiO, $ZrO_2$ and $Ce-ZrO_2$. Other bimetallic mixed oxides NCoZ, $NCoC^{4-12}Z$ has faster deactivation with low methanation activity. Finally, 2 wt.% Ce loading catalyst was found to be optimal coke resistant catalyst.

Characteristics of Conversion Coating of AZ31 Magnesium Alloy Formed in Chromium-Free Cerium-Based Solution (크롬 프리 세륨 용액에 의한 AZ31 마그네슘 합금의 화성 피막에 대한 특성 평가)

  • Kim, Myung Hwan;Lee, Dong Uk;Kwag, Sam-Tag;Moon, Myung-Jun
    • Journal of the Korean institute of surface engineering
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    • v.49 no.1
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    • pp.62-68
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    • 2016
  • A chromium-free Ce-based conversion coating formed by immersion in a solution containing cerium chloride and nitric acid on AZ31 magnesium alloy has been studied. The effects of acid pickling on the morphology and the corrosion resistance of the cerium conversion coating were investigated. The corrosion resistance of the conversion coating prepared on AZ31 Mg alloy after organic acid pickling was better than that of inorganic acid pickling. The morphology of the conversion-coated layer was observed using optical microscope and SEM. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.0 to $1.1{\mu}m$. The main elements of the conversion coating of AZ31 Mg alloy are Mg, O, Al, Ce and Zn by EDS analysis. The electrochemical polarization results showed that the Ce-based conversion coating could reduce the corrosion activity of the AZ31 Mg alloy substrates in the presence of chloride ions.

A Study on DME Conversion rate using New Catalyst (신 촉매를 이용한 DME 전환율에 관한 연구)

  • Jeong, I.S.
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.2
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    • pp.123-128
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    • 2011
  • It has been stand high in estimation to converse from Carbon dioxide to Dimethyl Ether in new alternative fuel energy division in 21C, especially Using of DME in point of view of transportation fuel has been discussed of a new clean energy which is very lower of exhaust gas than gasoline and diesel energy. In this paper it is used ZSM-5 and I developed new catalyst by addition of cerium to control acidity. The new catalyst was proved high conversion rate, when it was conversed from methanol to DME, there wasn't any additional material except DME and water, and I overlooked reaction temperature, reaction time, amount of catalyst, amount of added cerium, effect of water content in methanol, reaction temperature by making change of reaction time. I have conclude that conversion rate to DME was increased as increased of catalyst amounts. The best catalyst condition of without additional product was treated poisoning from ZSM-5 to 5% cerium and new catalyst was not effected in purity of fuel methanol.

Enhanced Catalytic Activity of Cu/Zn Catalyst by Ce Addition for Low Temperature Water Gas Shift Reaction (Ce 첨가에 따른 저온수성가스전이반응용 Cu/Zn 촉매의 활성 연구)

  • Byun, Chang Ki;Im, Hyo Bin;Park, Jihye;Baek, Jeonghun;Jeong, Jeongmin;Yoon, Wang Ria;Yi, Kwang Bok
    • Clean Technology
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    • v.21 no.3
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    • pp.200-206
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    • 2015
  • In order to investigate the effect of cerium oxide addition, Cu-ZnO-CeO2 catalysts were prepared using co-precipitation method for water gas shift (WGS) reaction. A series of Cu-ZnO-CeO2 catalyst with fixed Cu Content (50 wt%, calculated as CuO) and a given ceria content (e.g., 0, 5, 10, 20, 30, 40 wt%, calculated as CeO2) were tested for catalytic activity at a GHSV of 95,541 h-1, and a temperature range of 200 to 400 ℃. Cu-ZnO-CeO2 catalysts were characterized by using BET, SEM, XRD, H2-TPR, and XPS analysis. Varying composition of Cu-ZnO-CeO2 catlysts led the difference characteristics such as Cu dispersion, and binding energy. The optimum 10 wt% doping of cerium facilitated catalyst reduction at lower temperature and improved the catalyst performance greatly in terms of CO conversion. Cerium oxide added catalyst showed enhanced activities at higher temperature when it compared with the catalyst without cerium oxide. Consequently, ceria addition of optimal composition leads to enhanced catalytic activity which is attributed to enhanced Cu dispersion, lower binding energy, and hindered Cu metal agglomeration.

Increased Gene Expression in Cultured BEAS-2B Cells Treated with Metal Oxide Nanoparticles

  • Park, Eun-Jung;Park, Kwang-Sik
    • Toxicological Research
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    • v.25 no.4
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    • pp.195-201
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    • 2009
  • Recent publications showed that metal nanoparticles which are made from $TiO_2,\;CeO_2,\;Al_2O_3,\;CuCl_2,\;AgNO_3$ and $ZnO_2$ induced oxidative stress and pro-inflammatory effects in cultured cells and the responses seemed to be common toxic pathway of metal nanoparticles to the ultimate toxicity in animals as well as cellular level. In this study, we compared the gene expression induced by two different types of metal oxide nanoparticles, titanium dioxide nanoparticles (TNP) and cerium dioxide nanoparticles (CNP) using microarray analysis. About 50 genes including interleukin 6, interleukin 1, platelet-derived growth factor $\beta$, and leukemia inhibitory factor were induced in cultured BEAS2B cells treated with TNP 40 ppm. When we compared the induction levels of genes in TNP-treated cells to those in CNP-treated cells, the induction levels were very correlated in various gene categories (r=0.645). This may suggest a possible common toxic mechanism of metal oxide nanoparticles.